1. Field of the Invention
The present invention relates to a pigment dispersion composition having a good dispersibility and a good transparence, with such excellent anti-coating properties that the composition does not have an adverse influence on other materials, i.e. soaking into other coatings. The present invention further discloses a display apparatus such as a cathode ray tube and a method of manufacturing the apparatus.
2. Description of the Related Art
A color cathode ray tube is an example of a display apparatus for displaying an image by using emitting light from a phosphor layer. Conventionally, various methods for improving the contrast or color purity of such a display device have been proposed.
For example, Jpn. Pat. Appln. KOKAI Publications Nos. 48-17263, 52-63060 and 64-7457 each disclose a method in which a pigment layer having the same color as that of the emitting color from the phosphor layer is provided between the face plate and the phosphor layer.
Further, Jpn. Pat. Appln. KOKAI Publication No. 52-77578 discloses a method of forming a pigment layer by adding a pigment into a pre-coating solution before the phosphor layer is applied. Jpn. Pat. Appln. KOKAI Publications Nos. 53-69577 and 56-160746 each mention a method of embedding phosphor particles into a pigment layer which was made sticky.
Jpn. Pat. Appln. KOKAI Publication No. 53-65654 discloses that a phosphor screen is formed by forming a pigment layer containing a binder in the inner surface of a panel and then applying a phosphor suspension containing a photo-sensitive binder on the pigment layer, thereafter exposing the suspension to light and developing.
However, the above-described methods entail the below-described drawbacks, and therefore it is difficult to actually employ such a phosphor film having a pigment filter layer. First, the transparence of the pigment layer is insufficient, and the performance of the filter is poor, thus making it not possible to achieve good contrast properties. Second, the method involves a limited condition for work, and therefore defect-free filter layers cannot be constantly obtained.
According to the method of manufacturing a phosphor screen disclosed in Jpn. Pat. Appln. KOKAI Publication No. 64-7457, the pigment layer is formed by the slurry method, and after a while, the phosphor layer is formed by further using the slurry method. As a result, the number of the steps involved is twice as many as a general method, and the production cost is increased.